At present, communication services of M2M have been widely applied gradually, for example, to a logistics system, remote meter reading, smart home and the like. Providers of M2M services mainly develop the M2M services using an existing radio network, such as General Packet Radio Service (GPRS) network, Evolved Packet System (EPS) network and other Packet Switch (PS) networks. Since an M2M service has an obvious difference from a Human to Human (H2H) service, network deployment needs to be optimized, so that optimal network management and network communication quality can be obtained when the M2M service is applied.
The GPRS network is a second generation mobile communication network based on packet switch. In the third generation mobile communication system, the GPRS is evolved as Universal Mobile Telecommunication System Packet Switch (UMTS PS). FIG. 1 shows a diagram of network architecture of the UMTS PS according to a related art. As shown in FIG. 1, the network architecture comprises the following network elements:
a Radio Network System (RNS), which contains a NodeB and a Radio Network Controller (RNC), wherein the NodeB provides an air interface connection for a terminal; the RNC mainly manages radio resources and controls the NodeB; the RNC is connected with the NodeB through an lub interface; the terminal accesses a Packet Core network of a Universal Mobile Telecommunication System (UMTS) through the RNS;
a Serving GPRS Support Node (SGSN), which is connected with the RNS through an Iu interface, used for storing routing area location information of a user and taking charge of security and access control;
a Gateway GPRS Support Node (GGSN), which is connected with the SGSN through a Gn interface internally, used for allocating an IP address of a terminal and implementing a gateway function to an external network;
a Home Location Register (HLR), which is connected with the SGSN through a Gr interface and connected with the GGSN through a Gc interface, used for storing user subscription data and an SGSN address in which the user is currently located;
a Packet Data Network (PDN), which is connected with the GGSN through a Gi interface, used for providing a packet-based service network for a user.
In FIG. 1, Machine Type Communication (MTC) User Equipment (UE) needs to transmit data information to an MTC server or other MTC UEs through the GPRS network. The GPRS network establishes an RNC-SGSN-GGSN tunnel for this transmission, wherein the tunnel is based on a GPRS Tunneling Protocol (GTP) and the data information is reliably transmitted through the GTP tunnel.
The proposal of System Architecture Evolution (SAE) is to enable an Evolved Packet System (EPS) to provide higher transmission rate and lower transmission time delay, optimize packet-division and support mobility management among Evolved UTRAN (E-UTRAN), UTRAN, Wireless Local Area Network (WLAN) and other non-3GPP access networks.
FIG. 2 shows a diagram of a network system architecture of an EPS according to a related art. As shown in FIG. 2, the network element, i.e. Evolved NodeB (eNodeB), contained in an Evolved Radio access network (E-RAN) is used for providing radio resources for the access of a user. A Packet Data Network (PDN) is a network for providing services for a user. The EPC provides lower time delay and allows the access of more radio access systems, wherein the EPC comprises the network elements as follows.
A Mobility Management Entity (MME) is a control plane function entity and a server for temporarily storing user data, and is responsible for managing and storing a context of a UE (for example, user identifier, mobility management state, user security parameters and the like), allocating a temporary identifier for a user, and authenticating a user when a UE constantly resides in the tracking area or the network.
A Serving Gateway (SGW or S-GW) is a user plane entity and is responsible for processing routing of user plane data, terminating downlink data of a UE in an idle (ECM_IDLE) state, and managing and storing an SAR bearer context of a UE (for example, IP bearer service parameters, network internal routing information and the like). The SGW acts as an anchor of the user plane in the 3GPP system, and one user can have only one SGW at the same time.
A PDN Gateway (PGW or P-GW) is a gateway taking charge of the access of a UE to the PDN, also is a mobility anchor of 3GPP and non-3GPP access systems, and is used to allocate an IP address of a user; the function of the PGW also comprises policy enforcement and charging support. A user can access a plurality of PGWs at the same time. A Policy and Charging Enforcement Function (PCEF) also is located in the PGW.
A Policy and Charging Rules Function (PCRF) is responsible for providing policy control and charging rules for the PCEF.
A Home Subscriber Server (HSS) is responsible for storing user subscription data permanently. The content stored by the HSS comprises an International Mobile Subscriber Identification (IMSI) of a UE, and the IP address of the PGW.
Physically, the SGW and the PGW can be integrated; the user plane network element of the EPC system comprises the SGW and the PGW.
An MTC server is mainly responsible for information collection and data storage/process of an MTC UE and can perform necessary management for the MTC UE.
An MTC UE generally is responsible for gathering information of a number of collectors and accesses a core network through an RAN node to interact data with an MTC Server.
In FIG. 2, the MTC UE needs to transmit data information to the MTC Server or other MTC UEs through the EPS network. The SAE network establishes a GTP tunnel between the SGW and the PGW for this transmission and the data information is reliably transmitted through the GTP tunnel.
FIG. 3 shows a flowchart of a UE accessing an EPS network to perform an attachment procedure according to a related art. As shown in FIG. 3, the related attachment process mainly comprises the following steps (Step 301 to Step 318).
Step S301: in order to access an SAE network, the UE initiates a network attachment request to an eNodeB, wherein the request carries information such as IMSI, network access capability of the UE, and indication of requesting allocation of IP.
Step S302: the eNodeB selects for the UE an MME serving the UE and forwards the attachment request to the MME, and meanwhile carries important information, such as UE identifier, to the MME.
Step S303: the MME sends an authentication data request message (containing IMSI) to an HSS; the HSS first judges subscription data corresponding to the IMSI, if no subscription is found or the IMSI has been added to a black list, the HSS returns an authentication data response carrying an appropriate error cause to the MME; if the subscription data corresponding to the IMSI are found, the HSS returns an authentication data response message (containing authentication vector) to the MME.
The MME executes the authentication process to verify the legality of the IMSI of the terminal, and executes a security mode process to enable a secure connection.
Step S304: the MME sends a location update request message to the HSS of the home network to notify the area that the UE currently accesses, wherein the request message carries the identifier of the MME and the identifier of the UE.
Step S305: the HSS finds out the subscription user data of the UE according to the identifier of the UE and sends the subscription user data to the MME, wherein the user data mainly comprise information such as default Access Point Name (APN) and bandwidth size.
It should be noted that the MME receives the data, checks whether the UE is allowed to access the network and returns a user accepted response to the HSS; if the MME finds that the UE has problems such as roaming limit or access limit, the MME would forbid the attachment of the UE and notify the HSS.
Step S306: the HSS sends a location update acknowledgement response to the MME.
Step S307: the MME selects one S-GW for the LIE and sends a default bearer establishment request to the S-GW, wherein the request contains necessary information which the MME notifies the S-GW, such as the identifier of the UE, the identifier of the MME, the indication of allocating an IP address for the UE, default bandwidth information, and PDN GW address.
Step S308: the S-GW sends a default bearer establishment request to the PDN GW, wherein the request contains necessary information which the S-GW notifies the PDN GW, such as the address of the S-GW, default bandwidth information, and the indication of allocating an IP address for the UE.
Step S309: if necessary, the PDN GW requests a PCRF to configure policy and charging rules, and decision information for the UE.
Step S310: the PDN GW establishes a default bearer according to the policy and charging rules and decision information returned from the PCRF, and returns a bearer establishment response to the S-GW.
Step S311: the S-GW sends a default bearer establishment response to the MME.
Step S312: the MME sends an attachment accepted response to the eNodeB, indicating that the request of attaching the UE to the network is accepted, wherein the response carries the address of the SGW and a Tunnel Endpoint Identifier (TEID).
Step S313: the eNodeB sends a voice bearer establishment request to the UE, requiring the UE to store the important information of the bearer establishment and open a corresponding port, wherein the message carries information such as bearer network ID, PDN GW address, IP address allocated to the UE and bandwidth information.
Step S314: the UE sends a radio bearer establishment response to the eNodeB.
Step S315: the eNodeB notifies the MME that the attachment procedure is completed.
Step S316: the MME sends a bearer update request to the S-GW, to notify the identifier and address of the eNodeB serving the UE.
Step S317: the S-GW sends a bearer update response to the MME.
Step S318: if the PDN GW is not specified by the HSS, the MME sends a location update request to the HSS, to notify the HSS of the address information of the PDN GW serving the UE; the HSS updates the information.
FIG. 4 shows a flowchart of a UE accessing a GPRS network to perform an attachment procedure according to a related art. As shown in FIG. 4, the related attachment process mainly comprises the following steps (Step 401 to Step 407).
Step S401: a user initiates an attachment request message to an SGSN through an RNS for the first time, wherein the request message carries parameters such as attachment type and IMSI; the RNS routes the message to the SGSN according to the load condition of the RNS, with the IMSI of the user as request identification.
Step S402: the SGSN requests an HLR to authenticate the IMSI; the HLR downloads authentication parameters according to the IMSI; and the SGSN authenticates the UE.
Step S403: the SGSN sends a location update request to the HLR, wherein the request carries parameters such as SGSN number and address, and IMSI.
Step S404: the HLR downloads subscription data corresponding to the IMSI for the SGSN; the SGSN performs an access control check for the ME to check whether the UE has an area limit or access limit, and then returns a data insertion response to the HLR.
Step S405: the HLR confirms the location update message and sends a location update response to the SGSN. At this moment, if the location update request is rejected by the HLR, the SGSN would reject the attachment request of the UE.
Step S406: the SGSN allocates a Packet-Temporary Mobile Subscriber Identity (P-TMSI) for the user, and then sends to the UE an attachment accepted message carrying information such as the P-TMSI allocated for the UE.
Step S407: if the P-TMSI is updated, the Mobile Station (MS) returns an attachment completed message to the SGSN to confirm; the GRPS attachment procedure is completed.
According to the existing PS network architecture described in FIG. 1 and FIG. 2, and the processes of the existing terminal attaching to a network shown in FIG. 3 and FIG. 4, the existing terminal equipment, such as a cell phone, can receive a radio signal transmitted from a radio access network and attach to the network of an operator through the radio access network, and then carry out services such as a voice call.
The M2M service is a global machine type communication service which is just rising and is gradually put on the industrialization agenda. The M2M service enables each industry and each individual to enjoy the convenience of information service anytime and anywhere, by collecting information data through an M2M terminal in a sensor network and then transmitting the information data through the network. The M2M can be widely applied to industry applications, family applications, individual applications and so on. In the industry applications, the service comprises traffic monitoring, smart electric network, building alarm, sea rescue, vending machine, drive pay and so on. In the family applications, the service comprises automatic meter reading, temperature control and so on. In the individual applications, the service comprises life detection, remote diagnosis and so on.
The communication objects of the M2M are machine to machine, and man to machine. The data communication between one or more machines is defined as Machine Type Communication (MTC), and this condition needs few man-machine interactions. A machine participating in the MTC is defined as MTC equipment. The MTC equipment is a terminal of an MTC user, and this terminal can communicate with MTC equipment and an MTC server through a Public Land Mobile Network (PLMN) network. Mobile Equipment (ME) is an additional functional module of the MTC equipment, and the functional module is configured to enable the MTC equipment to access a radio network (for example, EPS network, GPRS network and the like). The MTC server manages and monitors the MTC equipment.
Since the MTC equipment mostly is the equipment of a specific application in different scenes, the MTC equipment is various in types and huge in number, for example, the equipment used in automatic meter reading is different from that used in life detection. Meanwhile, the MTC equipment also has different features due to different applications, for example, elevator equipment such as a lift has low mobility and PS only attribute, while a monitor and alarm equipment has features such as low-data-amount transmission and high availability, besides low mobility and PS only attribute. Therefore, the M2M equipment has many aspects different from the H2H equipment in application, specifically comprising: (1) the M2M terminals are huge in number, far more than the H2H terminals in quantity; thus, the terminal identification may not use the IMSI identification defined by the existing H2H terminal; (2) the M2M terminal is mainly for the application with low mobility and more than 90% of the M2M terminals are immoveable; thus, it has a big difference from the related art in mobility management (for example, the network does not need to perform location update process frequently); (3) the M2M terminal is mainly for the application with low data amount, which has a big difference from the services with high-bandwidth channel provided by the existing network; thus, the transmission mode of the network in the aspect of low data amount has a big difference from the related art; (4) other aspects, for example, the network needs to process the MTC equipment group and meet the requirement of each feature of the MTC terminal, for example, time control, MTC monitor and the like; all the above can only be satisfied by optimizing the existing network.
With the increasing use of the M2M applications, the mass development of the M2M terminals in quantity and the M2M application mode have a great difference from the existing H2H application; therefore, for different operators, the adoption of the existing network can not meet the requirement of the M2M services. Since the load of the existing network can not meet the requirement of the future M2M services, the operators need to optimize and deploy the network so as to meet the growing requirement of the M2M applications.